1. Field of the Invention
This invention relates to a video camera capable of photographing in a moving image mode and a still image mode.
2. Description of the Prior Art
Video cameras are in practical use which have a still image mode for photographing a subject as a still image in addition to a moving image mode for continuously photographing the subject. A still image is recorded, for example, in a PCM area on video tape. An image signal taken in the still image mode can be output in a printed form by using a video printer or the like.
Memory is usually used for photographing a subject in the still image mode. That is, an image photographed in the still image mode is once stored in a memory for each field or frame, and the stored contents in the memory are continuously output to provide a still image. The still image provided synchronizes with the video signal.
In order to enable photographing in the still image mode, a mechanical shutter, for example, is provided on the video camera. When a still image is desired, the mechanical shutter is switched from the open status to the closed status at a desired timing. At the same time, a control is done so that the CCD image pickup device is not exposed as long as the closed status of the mechanical shutter is maintained.
During photographing in the still image mode, the mechanical shutter is held in the closed status. Therefore, light to be otherwise injected to the video camera is being blocked. When the mechanical shutter is changed to the open status to switch the mode from the still image mode to the moving image mode, a large amount of light is injected at once to the video camera. This occurs, in particular, when photographing a moving image in an outdoor brightness after photographing a still image in an indoor darkness.
Moreover, if there is a large change in photographed scene upon transition from the still image mode to the moving image mode, it takes much time for automatic functions such as automatic focusing (called AF), automatic white balancing (called AWB), automatic exposure (called AE), and so forth, to establish their optimum conditions for the image of the latter moving image mode. This causes an initial portion of the image photographed in the moving image mode to be recorded as an unclear image when the mode is changed from the still image mode to the moving image mode.